Abstract: The neonatal blanket of this invention provides a generally elongated hemispheroidal, self-supporting thermal barrier for use with neonatal infants on open radiant warmer beds or convection-warmed infant incubators. The blanket can be formed from a single sheet of flexible clear plastic vinyl of similar material, shaped to provide a concave central cavity of a size to generally accomodate a neonatal infant, and having a relatively narrow, flat edge portion that extends around the blanket's perimeter. In use, the blanket is placed completely over the infant, so that its inner surface is close to but does not contact the infant's skin, and the flat edge portion both helps to support the blanket and provide an effective and efficient seal with the bedding material below. Thus, the blanket captures a volume of dead air space around the infant, which helps to reduce convective air currents within the infant's thermal microenvironment.